Pressure sensitive record material



Patented Apr. 25, 1950 2,505,475 PRESSURE SENSITIVE RECORD MATERIAL Barrett K. Green, Dayton, National Cash Register C Ohio, assignor to The ompany, Dayton, Ohio,

a corporation of Maryland No Drawing. Original application November 8, 1947, Serial No. 784,938. Divided and this application November 10, 1948, Serial No. 59,425

20 Claims. i

This invention relates to improvements in pressure-sensitive record material. This application is a division of the pending application of Barrett K. Green, Serial No. 784,938, filed November 8, 1947, for Pressure-sensitive record material.

The principal object of this invention is to provide a pressure-sensitive record material on which a mark of distinctive color may be produced by the mere application of localized pressure and which is not subject to the disadvantages inherent in the pressure-sensitive record material disclosed in United States Letters Patent No. 2,299,693, patented October 20, 1942, on the application filed by Barrett K. Green on February 23, 1940. That patent discloses a pressure-sensitive record material including the combination of an insulating medium, a rupturable solid material such as gum dammar, having included therein interspersed droplets of a plurality of liquid reagents, which are chemically reactive to produce a distinctive color in the record material at the points of application of localized pressure thereto, such pressure rupturing the insulating medium to permit chemical reaction between the two liquid reagents. The two reagents disclosed in this patent are gallic acid and ferric ammonium sulphate, each dissolved in glyccrine. These reagents are ionized by the glycerine, which constitutes an ionizing medium, and the chemical reaction proceeds by interchange of ions when the two solutions are allowed to mix, upon the rupture of the insulating medium. The reaction disclosed in that patent depends upon the presence of the reagents in an ionizing medium. However, any available ionizing medium is hygroscopic, with the result that the record material made in accordance with this patent is sensitive to an excess of moisture, and conditions of high humidity may cause the insulating medium to cease to be effective, with the result that the chemical reaction takes place without any application of localized pressure, and the record material is stained and discolored, so that it ceases to be useful.

As stated above, the principal object of the present invention is to provide a pressure-sensitive record material that is not subject to the defects and disadvantages of that disclosed in Patent No. 2,299,693, as indicated above.

Another object of the present inventionis to provide a record material upon which a mark of distinctive color may be produced, at the points of application of localized pressure thereto, by such mere application of localized pressure, and

which will not become discolored or stained due to the effect of light, atmospheric conditions, or aging.

In short, it is the object of this invention to provide a pressure-sensitive record material in which the mark of distinctive color will be produced only at the points of application of localized pressure, and at no other points, and under no other conditions.

Another object of this invention is to provide a pressure-sensitive record material in which the mark of distinctive color is produced by the chemical reaction of color-forming reactants, in the absence of any liquid ionizing medium therefor.

A further object of this invention is to provide a pressure-sensitive record material in which a mark of distinctive color is produced by a reaction between solid particles of color-forming reactants.

Further objects, and objects relating to details and economies of production, will definitely appear from the detailed description to follow. The objects of this invention have been attained by the several embodiments thereof described in detail in the following specification. This invention is clearly defined and pointed out .in the appended claims.

In general, the present invention contemplates a pressure-sensitive record material comprising, in combination, a plurality of adsorption color-forming reactants, such reactants being s0 selected that they react, in the absence of a liquid ionizing medium for the reactants, to form a distinctive color when brought into adsorption contact with each other, and a solid insulating medium insulating said reactants from color-forming reaction contact with each other. Upon application of localized pressure to the record material, as by drawing a stylu across it, the insulating medium is ruptured at the points of application of said localized pressure, and such rupture permits color-forming reaction contact between the reactants at such points, in the absence of any liquid ionizing medium for said reactants. The result is that a mark of distinctive color is produced by the mere application of localized pressure.

The color-forming action employed is of the so-called, adsorption type in which an inorganic material causes a color change in an organic material in adsorption contact therewith.

Of the reactant materials employed the organic material is an electron donor aromatic compound having a double bond system which is convertible to a more highly polarized conjugated form upon taking part in an electron acceptor-donor solid surface chemical reaction, giving it a distinctive color, and the inorganic material is a material which is an acid relative to the organic material so as to be an electron acceptor when in adsorption contact therewith. Both materials are in fine particle form in order to furnish a large reactant surface area per unit area of the record material which enhancesthe depth of color per unit area of the record material. I I

In the preferred form of this invention, both of the color-forming reactants, as well as the insulating medium, are in the solid state, and the color-forming reaction takes place upon "mere contact of solid particles of the reactants. 'A pressure-sensitive record material may be provided in which the solid particles of a plurality of color-forming reactants are separated by a solid insulating medium, which insulatesthe particles stratum-Tamin reaction contact with each other. The rupture of this solid insulating m ediiimby the application of localized pressure permits the solid particles of "color-forming react'ant'sfto react with each other, at the points of appli c fon of such pressure, to produce the mark of distinctive color. According to one form of this invention, solid particles of one of the colorfarm n re'actants'are carried by and dispersed ina'o ia'msuianng medium, to whicha coating of sol"d particles of another color-forming reactan't is appu'e'q, In this case, the application of localized pressure ruptures the solid insulating medium at the points of application of such pressure fanclbrings about color-forming reaction contact between the solid particles of colorforr'ning reactants at such'points, thus producing 'the'mark of distinctive color. Preferably, this pressure-sensitive record material includes a baseweb, such as a fibrous web of paper or the like, to which the coating of solid insulating medium andthe color-forming reactants is applied.

'Since'itis difiicult toshow precisely the spatial relationship between the solidparticles'of colbr-forming reactants, the solid insulating medium, and the base web, it is preferred not to attempt to illustrate any embodiment of this invention'by drawings.

In the following examples, there will be'described embodiments of this invention, by means of "which the objects of the invention have been successfully attained,

One pressure-sensitive record material constitutingan embodiment of this invention that has been successfully made consists of a web of paper having applied thereto a coating comprisingcasein as the solid insulating medium and two color-forming reactants; namely, kaolin and the compound bis (p-dimethylaminophenyl) methanol, also known as Michlers hydrol and having the structure In this record material, the casein forms the solid insulating medium, insulating the solid particles of kaolin and Michlers hydrol from color-forming reaction contact with each other until the application of localized pressure, ruptures the insulating medium at the points of'application of such pressure, permitting colorforming reaction contact between the particles, producin a dark blue mark. The record material is normally white or light gray in color.

This record material has been made successfully by'coa'ting a base webof paper with a solution of casein having sdlid particles of kaolin dispersed therein, the ratio of kaolin to casein 'being about ten to one. was dried and suitably calendered, and then the The paper so coated coated side of the paper was treated with a 3% by weight solution of Michlers hydrol dissolved in am alcohol saturated with potassium carbonate. Theexcess'of this solution was removed,

and the treated paper was dried, evaporating the "solvent, and was then ready for use.

According to'this embodimentgthecasein constitutes the solid medium, insulating the solid particles of kaolin'andof methyl ether of Michlers hydrol from color-formin 'reaction'contact with each other, and, When'this solidinsulating medium is ruptured'by the applicationof localizedpressure, color-forming reaction contact between the particlesis permitted at the'points of application of such pressure, producing-a dark blue'mark upon the normally white or grayish recordmaterial atsuch points.

The record'material constituting this embodiment of the invention has been madesuccessfully by-coating paper with a casein solution having dispersed therein soli'd-particles of kaolin, the ratio-by weight-of kaolin to casein being about tento one. The coatingthus applied having been 1dried, the coated side ofthe'paper was then itreated with a 3% by weight solution of methyl ether of Michlers hydrol in ethylialcohol saturated with potassium carbonate. The excess of this-solution wasremovedand the treated paper was dried to remove the solvent.

When the ingredients of eitherembodiment are applied to thepaper as a coatingthereon, such coating should weigh about .0023; pound per square foot of surface and l 1ave a thickness of the order of from .0095 to .OOlinch. The thick ness of the coating variea; of course, with the treatment to which;the record material is sub-- jected in finishing. The solid particles of; kaolin in this record material may be of about the order of ten microns in diameter, although considerable variation in -particle size is possible without any ill effects. Particle sizeof t-he organic reactants is largelydetermined 1 by the method of application of those-ingredients. The particles of these reactants; may be as large as ten microns in diameter and frequently aremuch m ll r.

page ic film forming hydrophilicf'collo'idsubrstances such fas gelatin, "mahyrceuuiese; starch, polyvinyl alcohol, and animal 'glue 'are representative materials that 'may be "substituted for casein' as the solid insulating medium. Ally""of the following inorganic materials may be substituted for kaolin a one of the color-forming reactants: attapulgite (Attapulgus clay), pyrophyllite, talc, bentonite, halloysite, calcium sulphate, calcium citrate, magnesium trisilicate, zinc sulphide, zirconium dioxide. calcium phosphate, barium sulphate, and calcium fluoride. When any of these materials are substituted for the kaolin in this combination, the resulting record material will be white or bluish white in color, and a dark blue mark will appear thereon as the result of the application of localized pressure.

One method that has been used successfully to make the pressure-sensitive record materials described above is as follows: A slurry of kaolin and Water was prepared including fifty parts by weight of kaolin to fifty parts by weight of water, and a small amount of a suitable dispersing agent, such as sodium metaphosphate, for instance, in the proportion of 0.075% by weight was added to facilitate the dispersion of the particles of kaolin throughout the slurry. The addition of this dispersing agent reduces the viscosity of the slurry considerably, thus facilitating its mixing and application and also preventin the setting of the solid particles of kaolin. A 20% by weight solution of casein in water was formed by, first, dispersing the casein in cold water by stirring for fifteen minutes at room temperature and, then, heating up to 60 degrees centigrade. Five parts by weight of a 28% ammonium hydroxide solution-that is, one having a specific gravity of 25.9 315., at

were then added to the hot casein solution, which was stirred for about fifteen minutes and allowed to cool to room temperature. The kaolin slurry and the alkaline casein solution were then thoroughly mixed and blended in the ratio of ten parts by weight of kaolin to one part of casein, and, at this stage, a small percentage-for instance, about 0.05% by weight-of tributyl phosphate in alcohol, or other anti-foaming agent, was added. This mixture of the kaolin slurry and the casein solution was then applied as a coating to the paper, and the coated paper was dried and calendered or treated in any desired way to give the proper surface finish. A solution in toluene of about 3% by weight of the his (p-dimethylaminophenyl) methane derivative was then applied to the coated side of the paper, the excess of this solution was removed in any suitable way, as by passing under a doctor blade, and then the treated paper was dried to evaporate the toluene and was ready for use.

The methods and processes of making pressure-sensitive record material disclosed herein are not claimed in this application but are disclosed and claimed in the pending application of Barrett K. Green, Serial No. 784,939, filed November 8, 1947, for Process for making pressuresensitive record material, and in the division thereof, Serial No. 63,214, filed December 2, 1948.

It is understood that the pressure-sensitive record material described herein is susceptible of considerable variation without departing from the spirit of the invention.

What is claimed is:

1. Pressure-sensitive record material including the combination of a supporting member, a plurality of adsorption color-forming reactants in the solid state, so selected as to react in the absence of a liquid ionizing medium for the react- 6, ants to form a distinctive color when brought into contact with each other, at least one of said reactants being an inorganic compound and at least another of said reactants being an organic compound, disposed in proximity to each other, and a solid insulating medium, derived from an organic film-forming hydrophilic colloid substance, insulating said reactants from colorforming reaction contact with each other, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit color-forming reaction contact between the reactants at such points, whereby a mark of distinctive color is produced by mere application of localized pressure, one of said color reactants being an organic compound of the general strucwherein R is selected from the group consisting of OH and O-CI-Is, and another of the reactants being an inorganic material in fine particle form to provide a large adsorbent surface area and which is an acid relative to the organic compound so as to be an electron acceptor when in adsorption contact with the organic compound, said organic compound and the organic material being adsorbable one upon the other.

2. The record material of claim 1 in which the inorganic one of the color-forming reactants; is kaolin.

3. The record material of claim 2 in which the solid insulating medium is casein.

4. Pressure-sensitive record material including the combination of a supporting member, solid particles of a plurality of adsorption color-forming reactants disposed in contiguity to each other, and a solid insulating medium, derived from an organic film-forming hydrophilic substance, insulating said solid reactant particles from colorforming reaction contact with each other, at least one of the reactants being an inorganic compound and at least another of the reactants being an organic compound, said reactants being so selected as to react to form a distinctive color when particles of each are brought into adsorption contact, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit color-forming reaction contact of;

the solid reactant particles at such points, whereby a mark of distinctive color is produced by mere Pplication of localized pressure, one of said color-forming reactants being an organic compound of the general structure wherein R is selected from the group consisting of OH and 0-CH3, and wherein the inorganic compound is in fine particle form providing a large adsorbent surface area and which is an acid relative to the organic reactant so as to be an electron acceptor when in adsorption contact with said organic compound, and said organic and inorganic reactants being adsorbable one upon the other.

a -rue "record iii'aterial of? lam-4 m which tlie inorgani'cone of the co'lor 'forming rea'c'tz'mt's is -6QTlie record inaterialof mar 5'ih "which the solidinsulating mediu'mis casein. I M

7. Pressure sensitive" record material including the combination of a e supporting member, a solid insulatingmedium-derived from anforganic 'jfil'mforming 3 hydrophilic colloid substance, solid particles of a first adsorption colorformingreactant dispersed therein and solid particles of a "second adsorption om-forming reactant "deposited thereon, said solid insulating mediu'r'niinsulatin'g said solid reactant particles from color; ormi-n reaction 'contactw'ith' each other, one of said reactar'its being 1 an inorganic compound and "the otherrea'ctant being an'organic c'ornpoii-niiand said reactants being so selected as to react,'i'n the solid state, to form a distinctive color when brought into adsorption contact with each other, the application of localized pressure to the record material rupturing said=insulating medium at the points of application of such pressure to permit color-forming reaction contact of the solid reactant particles at such points, whereby a mark of distinctive color isproduced by'mere application of localized pressure, saidsecond color iforin in'g reactant being an organic compound of the general structure The recordmaterial of claim 8 in "which the solid insulating medium is casein v 10. Pressure sensitive record material including the'combinatio'n of a base web and "a coating thereon, said coating including a plurality of adsorption "color-forming reactants in "thesolid state, so selected as to react in theabs'ence of an ioni'Zi ng Inediu-m to forma distinctive c'olorwhn brought into adsorption contact with-each other, and disposedin proximity to each other, at least one'of 'said reactants being an inorganiccompound'and at least another of said're'actants r' i itj mpw i a .7 ing in um, deri df rom'j n organic lmf'o niing hydrophilic-colloid substance; -1 are said reactants from;'coionrqnn ng react on contact with eacnorhe the appli'c'ation qf localized ressur "to" the record material rupturing; said ulaiting medium at the points of 'fapplication of Such-"pressure to -p'ermjit color-forming reaction Contact betwe'n the reactants at' "such w ereby amark OfdiS'tincti e' color produced by 'ere application of localized pressure; one of saidfreactants being organic compound of the generarstructure wne einn is selected from theg roup consisting of OH" a'Iid"O'-'-CH3,f and the inorganic material being in fine particle 'form to previaea large-adsdrp surface area andwhich 'is' an saddentivetothe organic compound was be'an'ews- ,7 tron acceptor whe in' adsorption contact'with the 'For'ganic compound, the organic 'c'o mpound and organic material being adso'rbable ondupon the'other.

1-1. The 'record material or claim 10" in which the inorganic one of'the 'color- 'forrh'ing reactants is Kaolin.

12. The record rn'aterialofclaim-*ll' -lnwhich the solid insulating medium is casein.

13. The record material of claim 1 in which R is OH. 7

14. The record material of claim 4 in which R l5. The record material of cla-i m '7 in whichR is OH,

The r'ecordmaterial of claim 10 in which R Q t i. i.

:1 7." Ih e record material of-claim 1 in which R soec I. a .l

18. ,The i'ecor d material of claim 4 inwhich R- 9,- H &s..\/

l9. The record material of claim 7 in which R- QQ a. .c y

20. The record material of claim 10 in which R -0113. v N

BARRETT K-GREEN.

REFERENCES CITED The following'references"are of i'ecord'in the file of this patent:

550,332 Great Britain Jan; 4; 19 13 

1. PRESSURE-SENSITIVE RECORD-MATERIAL INCLUDING THE CONBINATION OF A SUPPORTING MEMBER, A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS IN THE SOLID STATE, SO SELECTED AS TO REACT IN THE ABSENCE OF A LIQUID IONIZING MEDIUM FOR THE REACTANTS TO FORM A DISTINCTIVE COLOR WHEN BROUGHT INTO CONTACT WITH EACH OTHER, AT LEAST ONE OF SAID REACTANTS BEING AN INORGANIC COMPOUND AND AT LEAST ANOTHER OF SAID REACTANTS BEING AN ORGANIC COMPOUND, DISPOSED IN PROXIMITY TO EACH OTHER, AND A SOLID INSULATING MEDIUM, DERIVED FROM AN ORGANIC FILM-FORMING HYDROPHILIC COLLOID SUBSTANCE, INSULATING SAID REACTANTS FROM COLORFORMING REACTION CONTACT WITH EACH OTHER, THE APPLICATION OF LOCALIZED PRESSURE TO THE RECORD MATERIAL RUPTURING SAID INSULATING MEDIUM AT THE POINTS OF APPLICATION OF SUCH PRESSURE TO PERMIT COLOR-FORMING REACTION CONTACT BETWEEN THE REACTANTS AT SUCH POINTS, WHEREBY A MARK OF DISTINCITVE COLOR IS PRODUCED BY MERE APPLICATION OF LOCALIZED PRESSURE, ONE OF SAID COLOR REACTANTS BEING AN ORGANIC COMPOUND OF THE GENERAL STRUCTURE 